When linked characters or genes are inherited together through two or more generations,it is called

Drosophila melanogaster has $8$ chromosomes in its somatic cell. How many linkage groups will it have?

Genes $p, q,$ and $r$ are arranged on a chromosome. If the recombination frequency between $p$ and $q$ is $10 \%$,the recombination frequency between $q$ and $r$ is $20 \%$,and the recombination frequency between $p$ and $r$ is $10 \%$,what is the order of the genes on the chromosome?

Who put forward the "Theory of linkage"?

Two genes $R$ and $Y$ are located very close on the chromosomal linkage map of maize plant. When $RRYY$ and $rryy$ genotypes are hybridized,then $F_{2}$-segregation will show

Define/Explain: Linkage.